Motor Or Machine Is Making Abnormal Acoustic Noise; Inverter Generates Abnormal Noise; Motor Generates Heat Abnormally - Mitsubishi Electric FR-F740 EC Instruction Manual

Check first when you have troubles
7.6.2

Motor or machine is making abnormal acoustic noise

When operating the inverter with the carrier frequency of 3kHz or more set in Pr. 72, the carrier
frequency will automatically decrease if the output current of the inverter exceeds the value in
parenthesis of the rated output current in section A.1. This may cause the motor noise to in-
crease. But it is not a fault.
Check points Possible cause
Input signal
Parameter
Setting
Parameter
Setting
Others
Motor
7.6.3

Inverter generates abnormal noise

Check points Possible cause
Fan
7.6.4

Motor generates heat abnormally

Check points Possible cause
Motor
Main Circuit
Parameter
Setting
—
7 - 30
Disturbance due to EMI when frequency
command is given from analog input (ter-
minal 1, 2, 4).
No carrier frequency noises (metallic
noises) are generated.
Resonance occurs. (output frequency)
Resonance occurs. (carrier frequency)
Gain adjustment during PID control is
insufficient.
Mechanical looseness
Contact the motor manufacturer.
Operating with output phase loss
Fan cover was not correctly installed when
a cooling fan was replaced.
Motor fan is not working
(Dust is accumulated.)
Phase to phase insulation of the motor is
insufficient.
The inverter output voltage (U, V, W) are
unbalanced.
The Pr. 71 "Applied motor" setting is
wrong.
Motor current is large.
Countermeasures
Take countermeasures against EMI.
Increase the Pr. 74 "Input filter time con-
stant" if steady operation cannot be per-
formed due to EMI.
In the initial setting, Pr. 240 "Soft-PWM
operation selection" is enabled to change
motor noise to an unoffending complex
tone. Therefore, no carrier frequency
noises (metallic noises) are generated.
Set Pr. 240 = "0" to disable this function.
Set Pr. 31 to Pr. 36 "Frequency jump".
When it is desired to avoid resonance
attributable to the natural frequency of a
mechanical system, these parameters
allow resonant frequencies to be jumped.
Change Pr. 72 "PWM frequency selection"
setting.
Changing the PWM carrier frequency pro-
duces an effect on avoiding the resonance
frequency of a mechanical system or a
motor.
To stabilize the measured value, change
the proportional band (Pr. 129) to a larger
value, the integral time (Pr. 130) to a
slightly longer time, and the differential
time (Pr. 134) to a slightly shorter time.
Check the calibration of set point and
measured value.
Adjust machine/equipment so that there is
no mechanical looseness.
Check the motor wiring.
Countermeasures
Install a fan cover correctly.
Countermeasures
Clean the motor fan.
Improve the environment.
Check the insulation of the motor.
Check the output voltage of the inverter.
Check the insulation of the motor.
Check the Pr. 71 "Applied motor" setting.
Refer to section 7.6.11 "Motor current is
too large"
Troubleshooting
Refer to
page
3-44
6-198
6-185
6-56
6-185
6-328
—
—
Refer to
page
8-11
Refer to
page
—
—
8-2
6-93
7-33